Many instrumentation displays include gages and/or dials with rotatably mounted pointers. In many instances, designers desire the pointers to be illuminated. One known method for illuminating pointers is to construct the pointer out of light piping material that receives light from a fixed light source, remote from the pointer, possibly through additional light piping material.
Another known method of providing an illuminated pointer is to provide one or more light sources on the pointer, which light sources are connected to a power source through flexible contacts that allow the pointer to rotate while maintaining power supply to the light source on the pointer.
Still another attempt at providing an illuminated pointer appears in FIG. 1. The pointer 200 is back-lit by an electroluminescent lamp 202. The pointer 200 and the electroluminescent lamp 202 are connected to coil 204 which is mounted to the spindle of gage 208 so that as gage 208 causes its rotor (not shown) to rotate, the coil 204, electroluminescent lamp 202 and pointer 200 also rotate. When power is applied to primary coil 206, it is coupled to secondary coil 204, which rotates within primary coil 206, and which powers lamp 202.
The apparatus shown in FIG. 1 was disclosed in an unworkable implementation in Research Disclosure, No. 28985, May 1988. Furthermore, even if the apparatus shown were made workable, the brightness of pointer 200 would be limited because of the limited brightness of electroluminescent lamps.